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CHALLENGE

function highlight(strings, ...values) {
return strings.reduce((result, str, i) => {
const value = values[i - 1];
const formatted =
typeof value === "number"
? `[${value * 2}]`
: `<${String(value).toUpperCase()}>`;
return result + formatted + str;
});
}

const language = "javascript";
const year = 2015;
const feature = "templates";

const output = highlight`Language: ${language}, introduced in ${year}, feature: ${feature}!`;
console.log(output);
❀6πŸ‘2πŸ”₯2
CHALLENGE

const handler = {
get(target, prop, receiver) {
if (prop in target) {
return Reflect.get(target, prop, receiver) * 2;
}
return `Missing: ${prop}`;
},
set(target, prop, value) {
if (typeof value !== "number") {
throw new TypeError("Only numbers allowed");
}
return Reflect.set(target, prop, Math.abs(value));
},
};

const store = new Proxy({ gold: 10, silver: 5 }, handler);

store.bronze = -42;

console.log(store.gold);
console.log(store.bronze);
console.log(store.platinum);
❀4πŸ”₯3
❀4πŸ”₯2πŸ‘1
CHALLENGE

function* range(start, end) {
while (start < end) {
yield start++;
}
}

function* evens(iter) {
for (const val of iter) {
if (val % 2 === 0) yield val;
}
}

function* take(n, iter) {
let count = 0;
for (const val of iter) {
if (count++ >= n) return;
yield val;
}
}

function* pipeline() {
yield* take(3, evens(range(1, 20)));
yield* take(2, range(10, 15));
}

const result = [...pipeline()];
console.log(result);
πŸ”₯2πŸ‘1
πŸ€” axios Package Compromised; Malicious Versions Added a Trojan Dependency

Axios is an HTTP library that gets 100M+ downloads a week, largely due to its legacy popularity. An attacker took advantage of that to roll out a version with a malicious dependency including a remote access trojan (though Axios' codebase itself was fine). This is big, as even if you don’t use Axios, your dependencies might. Here's how to see if you're affected.

Ashish Kurmi
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❀4πŸ”₯4πŸ€”3🀩1
CHALLENGE

const delay = (ms, val) => new Promise(res => setTimeout(res, ms, val));

const p1 = delay(300, "alpha");
const p2 = Promise.reject("network error");
const p3 = delay(100, "gamma");
const p4 = Promise.reject("timeout");

Promise.allSettled([p1, p2, p3, p4]).then(results => {
const summary = results.map(r =>
r.status === "fulfilled"
? `ok:${r.value}`
: `fail:${r.reason}`
);
console.log(summary.join(" | "));
});
πŸ‘3πŸ”₯2❀1
CHALLENGE


const str = " Hello, World! ";

const result = str
.trim()
.split(", ")
.map((word, i) => {
if (i % 2 === 0) return word.toUpperCase();
return word.toLowerCase().replace("!", "@");
})
.reverse()
.join(" | ");

console.log(result);
❀3
πŸ”₯8❀5πŸ‘1
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πŸ‘5πŸ”₯2❀1
CHALLENGE

function Vehicle(make, model, year) {
this.make = make;
this.model = model;
this.year = year;
this.speed = 0;
}

Vehicle.prototype.accelerate = function (amount) {
this.speed += amount;
return this;
};

Vehicle.prototype.describe = function () {
return `${this.year} ${this.make} ${this.model} going ${this.speed}km/h`;
};

function ElectricVehicle(make, model, year, range) {
Vehicle.call(this, make, model, year);
this.range = range;
}

ElectricVehicle.prototype = Object.create(Vehicle.prototype);
ElectricVehicle.prototype.constructor = ElectricVehicle;

ElectricVehicle.prototype.describe = function () {
return Vehicle.prototype.describe.call(this) + ` | Range: ${this.range}km`;
};

const car = new ElectricVehicle("Tesla", "Model 3", 2023, 500);
car.accelerate(60).accelerate(40);

console.log(car.describe());
console.log(car instanceof ElectricVehicle);
console.log(car instanceof Vehicle);
console.log(car.constructor === ElectricVehicle);
❀2
✌️ JSIR: A High-Level IR for JavaScript from Google

Google has open sourced a new tool (JSIR) and proposed an industry-standard IR (Intermediate Representation – if an AST tells you what the code looks like, an IR tells you what it does) for JavaScript. Already used at Google for analysis and code transformation, the underlying idea could form a foundation for a new generation of tooling.

Zhixun Tan (Google)
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❀4πŸ‘4πŸ”₯2
CHALLENGE


function createUser(
name,
role = "viewer",
permissions = [role],
metadata = { createdBy: name, level: permissions.length }
) {
return { name, role, permissions, metadata };
}

const user1 = createUser("Carlos");
const user2 = createUser("Diana", "admin", ["read", "write", "delete"]);
const user3 = createUser("Eve", "editor", undefined, { createdBy: "system", level: 99 });

console.log(user1.role, user1.permissions, user1.metadata.level);
console.log(user2.metadata.createdBy, user2.permissions.length);
console.log(user3.permissions[0], user3.metadata.level);
❀1πŸ‘1πŸ”₯1
In CSS is DOOMed, Niels Leenheer shows off how he implemented a version of 1993's Doom using purely CSS rendering (with the game logic in JavaScript). Play it for yourself or check out the code.
πŸ”₯7❀4
CHALLENGE


const name = "Carlos";
const age = 28;
const score = 95;

const player = {
name,
age,
score,
greet() {
return `${this.name} (${this.age}) scored ${this.score}`;
},
get rank() {
return this.score >= 90 ? "Gold" : "Silver";
}
};

const { name: playerName, rank, greet } = player;

console.log(`${playerName} | ${rank} | ${greet.call(player)}`);
πŸ€”5❀2πŸ‘1